Power Automate enables file creation, updates, and storage across multiple services such as SharePoint, OneDrive, Dataverse, Azure Blob Storage, and external databases. However, sometimes a flow fails to write data to a file, leading to errors such as:
“Error writing to file: Unable to complete the file write operation.”
This guide explains:
Why the “Error Writing to File” error occurs.
How to diagnose the issue.
How to fix common file writing problems.
Step 1: Understanding Common Causes of the “Error Writing to File” Error
| Cause | Description |
|---|---|
| Insufficient permissions | The flow does not have write access to the file or folder. |
| File is locked | Another process or user is using the file, preventing modifications. |
| File does not exist | The flow is trying to update a file that has been deleted. |
| Incorrect file path | The specified location is incorrect or inaccessible. |
| Storage quota exceeded | The destination service has run out of storage. |
| File name contains special characters | Some characters are not allowed in file names. |
| File size limit exceeded | The file being written exceeds the platform’s allowed size. |
| Concurrent file access issue | Too many flow runs or users are trying to modify the file simultaneously. |
| File format issue | The flow is trying to write data in an unsupported format. |
Step 2: Diagnosing the Issue
2.1. Check the Flow Run History
- Open Power Automate (https://make.powerautomate.com).
- Click on My Flows → Select the affected flow.
- Go to Run History → Open a failed run.
- Look for an error message like:
Error writing to file: Access denied or file is locked. - Expand the action details to check:
- File name and path used in the flow.
- Error messages related to permissions, storage, or locking.
- API responses or system logs.
Step 3: Fixing Common “Error Writing to File” Issues
3.1. Fix Insufficient Permissions
Problem: The flow does not have permission to write to the file or folder.
Solution:
- Ensure that the user or service account running the flow has Edit or Write permissions on the file location.
- If using SharePoint, grant “Contribute” or “Edit” access to the flow’s connection.
- If using OneDrive, ensure the file is not shared as “View Only.”
How to Check & Fix SharePoint Permissions:
- Go to the SharePoint Document Library.
- Click on the file or folder → Manage Access.
- Ensure the Power Automate connection has Edit or Full Control.
- If needed, update the permissions via Power Automate “Grant Access to an Item or Folder” action.
3.2. Fix File Locking Issues
Problem: The file is being used by another user or process.
Solution:
- Wait a few minutes and retry the flow.
- Ensure no one is editing the file in Excel Online, Word, or another application.
- If using SharePoint, try disabling check-out requirements:
- Go to Library Settings > Versioning Settings.
- Set Require Check Out to No.
- If needed, use a delay action before retrying the file write operation.
3.3. Fix Missing or Deleted File Issues
Problem: The file being updated was deleted before the flow ran.
Solution:
- Before writing to a file, use “Get File Properties” to check if it exists.
- If the file is missing, create a new file dynamically before writing data.
- Use a “Condition” action to check file existence before proceeding.
3.4. Fix Incorrect File Path Issues
Problem: The specified file path is incorrect or inaccessible.
Solution:
- Ensure the path includes correct folder names and separators.
- If using SharePoint, use the absolute file path format:
/Shared Documents/Reports/AnnualReport.xlsx
- If dynamically generating a file name, ensure the full path is properly formed before writing.
3.5. Fix Storage Quota Exceeded Issues
Problem: The target storage (SharePoint, OneDrive, Dataverse, etc.) is full.
Solution:
- Delete unnecessary files to free up space.
- Check storage quotas for OneDrive, SharePoint, or Dataverse.
- If using Azure Blob Storage, increase the container’s allocated storage.
3.6. Fix Invalid File Name Issues
Problem: The file name contains special characters not supported by the destination service.
Solution:
- Remove restricted characters (
\ / : * ? " < > |) from file names. - Ensure file names are within the maximum allowed length (255 characters).
- Use replace expressions in Power Automate to clean up file names:
replace(replace(replace(FileName, '/', ''), '?', ''), '*', '')
3.7. Fix File Size Limit Exceeded Issues
Problem: The file being written exceeds the maximum allowed size.
Solution:
| Service | Max File Size |
|---|---|
| SharePoint | 250 MB (Standard) / 15 GB (Premium) |
| OneDrive | 250 MB (Standard) / 15 GB (Premium) |
| Dataverse | 128 MB (Standard) / 512 MB (Premium) |
| Azure Blob Storage | 5 TB |
- If a file is too large, try compressing or splitting it before writing.
- For SharePoint or OneDrive, enable chunked file uploads.
3.8. Fix Concurrent File Access Issues
Problem: Too many users or flows are trying to modify the file simultaneously.
Solution:
- Add a “Delay” action between write operations to reduce conflicts.
- If multiple flows access the same file, implement a locking mechanism using a flag file.
3.9. Fix File Format Issues
Problem: The flow is trying to write data in an unsupported format.
Solution:
- Ensure the correct file format is used for the destination service.
- Convert data to the expected format before writing (e.g.,
.xlsx,.csv).
Example: Convert CSV Data to JSON Before Writing to a File
Use “Parse JSON” action before writing JSON data to a file:
{
"Name": "John Doe",
"Email": "john.doe@example.com"
}
Step 4: Preventing Future “Error Writing to File” Issues
4.1. Best Practices to Avoid File Writing Errors
✅ Use absolute paths instead of relying on dynamic values.
✅ Ensure write permissions for the file and folder.
✅ Check if the file is locked before writing.
✅ Use a condition to validate file existence before writing.
✅ Ensure the file is in the correct format.
✅ Avoid exceeding file size limits.
✅ Implement retry policies to handle temporary issues.
Step 5: Set Up Alerts for File Writing Errors
- Open Power Automate → My Flows.
- Click Edit Flow → Add a “Send an email” action if file writing fails.
- Configure the email to alert users about failed file operations.